Automatic thread clamp for needle threads



July 11, 1933. A. H. WEIS 1,917,411

AUTOMATIC THREAD CLAMP FOR NEEDLE THREADS Filed July 21, 1951 Patented July 11, 1933 UNITED STATES PATENT OFFICE ALBERT IE. WEIS, OF NYACK, NEW YORK, ASSIGNOR TO THE METROPOLITAN SEWING MACHINE CORPORATION, OF NYACK, NEW YORK, A CORPORATION OEDELAWARE AUTOMATIC THREAD CLAMP FOR NEEDLE THREADS Application filed July 21,

This invention relates to sewing machines, more particularly to an improved automatic thread clamp for theneedle threads, the object of the invention being to provide a simple mechanism that will act on one or more threads as they pass from the tensions to the needles of a sewing machine, whereby each thread will be gripped and clamped uniformly to prevent or retard movement of the thread during such clamping action and to insure the drawing up of the needle loops to the bottom face of the fabric immediately after said loops have been cast off of the loop takers or loopers.

Another object is the provision of a thread clamping means which will permit the proper control of the needle threads, whereby they may pass through the tensions and nee-.

dles to form stitches in the work with a minimum drag on the thread, thereby to permit threads of delicate'character, suchas rayon, yarn and similar threads, (which have very little strength or twist) tobe used in the V needles of a sewing machine for stitching the fabrics.

Many threads are not strong enough to withstand suflicient tension for the stitching of various fabricsand yet draw up a smooth, tight stitch in the work. When suflicient tension is applied to the threads by-the ordinary tensions of a sewing machine, the drag is constant, and while the loops of needle threads are around the loopers or loop takers, a tight tension on these threads causes excessive strain and frequent breakage thereof. This will be eliminated by this improved automatic thread clamp which will clamp the threads momentarily, instantly as the thread loops are cast oil? of the loopers.

In some systems of sewing machines, the needle threads are directed from the tensions to a thread eyelet on the top of the needle A bar and from thence to the eyes of the needles. The needle bar action provides a. form of take-up for the needle threads, this arrangement depending principally on the elasticity of the thread to giveand take somewhat as the needle thread loops are on the loopers, and also depending on this elasticity to draw 1931. Serial No. 552,114.

in accomplishingthis task, since the tensions can be set with very. little drag 011 the threads each one being independent, and can have its respective adjustment, even though all the threads being used are not alike, and a uniform stitch can be made by the independent adjustment of thetensions to suit the character of thread and the material being stitched, so that the finished stitching will be uniform.

Another object of this improvement is to overcome the resistance against the feeding of the work which causes shirring and puck ering of delicate fabrics. When an even and constant tension is applied to the thread during the stitching cycle, the feed of the work takes place while the needle loops are around the-loopers, and if thethread tensions are tight during this feed movement, the previous stitch is subject to considerable strainand back drag. By loosening the tensions, this is overcome, but an objectionable stitch is frequently produced when the tension. on the threads'is too loose. Therefore, to overcome this objection and yet operate'with a comparatively loose tension on the needle threads, this improved thread nipper is provided to clamp the thread at the desired moment of each cycle of the machine, and at other times permit the thread to pass freely to the stitches.

In the drawing accompanying and forming a part of this specification, Fig. 1 illustrates the rear portion of the upper arm ofa wellknown Metropolitan top and bottom rotary shaft machine with the tensions and this im- 7 proved thread clamp applied thereto.

Fig.2 is a top viewof the tensions and v 7 thread clamp. up the loops as they are'cast off of the l0op-.

Fig 3 is a sectional view taken on the line 3-3 of Fig. 1, looking in the direction of the arrow, and is intended to illustrate more clearly the parts of the thread clamp, and Fig. 4 is a view of a triangular shaped cam. Similar characters of reference ind cate corresponding parts in the several views.

Before explaining in detail the present improvement and mode of operation thereof, I desire to have it understood that the invention is'not limited to the details of con-- struction and arrangement of parts which are illustrated in the accompanying drawing since the invention is capable of other embodiments, and that the phrase ology which I employ is for the purpose of description and not of limitation.

The upper arm of the sewing machine 1 has a top crank shaft 2, having three connecting rods 3 connecting the top shaft to the hottom shaft which also has a similar three- I throw crank shaft. The rear end of the shaft 2 carr es a hand wheel 4. Located on the shaft 2 is an eccentric 5 operating against a rigid arm 6 and a spring arm 7 of a lever 8, see Fig.

3. This lever is pivoted at 9 to an upstanding lug 10 carried by aplate 11. This Plate 11 is secured to the top surface of the arm 1 of the sewing machine by screws 12, and can readily be removed to give free access to the crank shaft connections. This plate is pro vlded wlth three depending tubular P101604 tions 13 to'feed oil'to the three cranks of the top shaft and these oil tubes communicate with channels 1 1 in the top surface ofthe plate to facilitate oiling.

The lever 8 1s provided with an arm 15 having two screws 16 holding and clamping against the arm 15, an adjustable extension 7 threads.

piece 17, to which is pivotally connected. at 18 the upstanding lug 19 of a thread clamp member 20. This thread clamp member is made in the form shown so as to clamp four The design of these parts is arranged to suit any number of threads required according to the machines equipment for stitching multiple seams.

The plate 11 is provided with an elevated portion 21 against which the member 20 acts, the sidewalls 22 of which have slots 23 to guide the threads 2 1 and keep them sepathe eccentric 5 with respect to the movement of the loopers and needles is such as to clamp the threads just prior to the thread loops being cast off of the loopers and immediately to release the threads after the stitch has been drawn up to the bottom surface of the goods.

The spring arm 7 of the lever 8 permits the use of cams or triangular eccentrics of irregular form as 5, Fig. 4, so that a quicker action than that which can be obtained from an ordinary eccentric can be had when needed. The spring arm will yield to compensate for any irregularities in the eccentric or cam and permit it to operate at high speed without noise. The rigid arm 6 insures a positive gripping action and the adjustable extension 17 permits adjustment of the clamping member by means of the elongated slots 16 to suit different sizes of threads from the thinnest to the thickest.

It is necessary for proper control of needle threads to have an independent tension on each thread because all threads are not alike. At times, different sizes of threads are used on the same machine. Some'thread has a tendency to twist and snarl if there is no tension whatever applied to it as it passes to the needles. This usually occurs with the automatic tension as it is opened. Therefore, the arrangement shown in my improvement comprises a constant tension on the thread which is adjustable.

sufiici-ent pressure to compress the threads to different sizes within reasonable limits, so that threads of different sizes can be clamped sufficiently to prevent movement thereof. 7

It is to be understood that by describing in detail herein any particular form, structure or arrangement, it is not intended to limit the invention beyond the terms of the,

loops being cast off the loopers and to release the threads after the stitch has been drawn up to the bottom surface of the goods and comprising a swinging clamping device carried by said top arm and movable in a vertical plane, means co-operating therewith for clamping the threads, and rockable means for operating said clamping device.

2. In a sewing machine having a top arm and a top shaft, the combination of an automatic thread clamping means effective to clamp the threads just prior to the thread loops being cast off the loopers and to release the threads after the stitch has been I In addition "thereto, the automatic thread clamp exerts drawn up to the bottom surface of the goods and comprising a swinging clamping device 'arried by said top arm, means co-operating therewith for independently guiding the threads, ano means for operating said clamping device comprising an eccentric and a swinging arm in engagement therewith.

3. In a sewing machine having a top arm and a top shaft, the combination of an automatic thread clamping means effective to clamp the threads just prior to the thread loops being cast 01f the loopers and to release the threads after the stitch has been drawn up to the bottom surface of the goods and comprising a clamping device carried by said top arm, means co-operating therewith for independently guiding the threads, and means for operating said clamping device comprising an eccentric and an arm co-operating therewith, said arm having a rigid member and a spring member.

4. In a sewing machine having a top arm and a top shaft, the combination of an automatic thread clamping means effective to clamp the threads just prior to the thread loops being cast off the loopers and to release the threads after the sti ch has been drawn up to the bottom surface of the goods and comprising a clamping device carried by said top arm, means cooperating therewith for independently guiding the threads, and means for operating said clamping device comprising an eccentric and an arm co-operating therewith, said arm having a rigid member and a spring member and said eccentric having an irregular formation.

5. In a sewing machine having a top arm and a top shaft, a thread clamping means effective to clamp the threads independently just prior to the thread loops being cast oif the loopers and to release the threads after the stitch has been drawn up to the bottom surface of the goods, and comprising a member having thread guides therein, a swinging co-opcr'ating clamping member carried by the top arm, and means for operating said clamping member and comprising a pivoted arm, a swinging arm connected therewith, and an eccentric engaging said last arm.

6. In a sewing machine having a top arm and a top shaft, a thread clamping means effective to clamp the threads independently just prior to the thread loops being cast off the loopers and to release the threads after the stitch has been drawn up to the bottom surface of the goods, and comprising a member having thread guides therein, a co-operating clamping member carried by the top arm and means for operating said clamping in ember and comprising a pivoted arm, an arm connected therewith, and an eccentric co-opcrating with said last arm, said last arm having a rigid member co-operating with one side of the eccentric and a spring member co-operating with the other side thereof.

In a sewing machine having a top arm and a crank shaft therein, a thread clamping member pivotally secured to said top arm, and means for raising and lowering said thread clamping member and comprising an eccentric carried by said crank shaft and a swinging arm in engagement therewith.

8. In asewing machine having a top arm and a crank shaft therein, a thread clamping member pivotally secured to said top arm, and means for raising and lowering said thread clamping member and comprising an eccentric carried by said crank shaft and an arm co-operating therewith, said arm having a rigid member and a spring member effective to yield and compensate for any irregularities in the eccentric.

9. In a sewing machine having a top arm and a crank shaft therein, a thread clamping member pivotally secured to said top arm, and means for raising and lowering said thread clamping member and comprising an eccentric carried by said crank shaft and an arm co-operating therewith, said arm having a rigid member and a spring member effective to yield and compensate for any lrregulari- V ties in the eccentric, and said eccentric having an irregular form.

10. In a sewing machine having a top arm and a crank shaft therein, a thread clamping member pivotally secured to said top arm, and means for raising and lowering said thread clamping member and comprising an eccentric carried by said crank shaft, and a swinging arm in engagement therewith, and means for adjusting said thread clamping member to different sizes of threads.

-11. In a sewing machine having a top arm and a top shaft and provided with thread tensions, an automatic thread clamping means located between said tensions and the forward end of the arm and comprising a memher having thread grooves, a co-operating clamping member carried by the top arm, a pivoted adjustable arm for the clamping member, a lever connected with said arm and having a rigid member and a spring member, and a cam carried by said top shaft co-operating with said rigid and spring members for operating said clamping member and timed to clamp the threads just prior to the thread loops being cast off the loopers and to release the threads after the stitch has been drawn up to the bottom surface of the goods. 7

Signed at Nyack, New York, this 17th day of J iily, 1931. i

ALBERT H. WEIS. 

